Someone who starts a conversation with you when in fact you have no wish to speak to them, then talks for ages without giving you an opportunity to excuse yourself without appearing rude.

Hostage talkers either enjoy making you uncomfortable or are completely oblivious to the fact that they are not wanted. People likely to be hostage talkers are mothers, younger brothers, bosses or people to whom you owe money.

Dave: Why isn't Mike here yet?
Steve: I think he ran into Linda in the hallway.
Dave: Damn, then he'll be ages. She's a hostage talker.